This invention relates generally to improvements in oil seals and related seal systems for preventing oil leakage in connection with rotating shafts, and particularly in connection with relatively high speed rotating shafts in turbomachines and the like. More specifically, this invention relates to an improved oil seal utilizing principles of dynamic air-oil separation to seal passage of a rotatable shaft through an end wall of a bearing housing.
In turbomachinery, a rotatable shaft is commonly supported by appropriate journal and thrust bearings mounted within a bearing housing, wherein oil is circulated from a sump to lubricate the bearings. The rotatable shaft extends through an end wall of the bearing housing, at one or both ends thereof, for appropriate connection to other components of the turbomachine, such as a turbine wheel, compressor wheel, or other suitable shaft drive means or shaft load. Examples of such turbomachines includes turbochargers, turbocompressors, gas turbine engines, air turbine starter motors, and the like.
In general terms, it is highly desirable to minimize and eliminate oil leakage along the rotating shaft and through the end wall of the bearing housing. Alternately stated, it is desirable to confine circulatory oil flow to the interior of the bearing housing. In this regard, a wide variety of oil seal configurations have been proposed in efforts to overcome oil leakage problems. However, the high speed shaft rotation and other operating conditions in a typical turbomachine environment have generally precluded complete elimination of the oil leakage. That is, high speed shaft rotation tends to result in relatively rapid wear of seal structures and early onset of oil leakage. This problem is compounded by high temperature operating environments and adverse differential pressures which may be present on opposite sides of the bearing housing end wall.
There exists, therefore, a continuing need for further improvements in oil seal structures for use in turbomachines and the like, for substantially eliminating oil leakage through the end wall of a bearing housing, notwithstanding high speed shaft rotation and high temperature operating conditions. The present invention fulfills these needs and provides further related advantages.